A few days after Mikal Siele’s long journey from Eritrea ended in Arlington County this spring, she found herself in a nondescript office building, staring at a series of drawings, trying to think of the right English words.

What’s happening in this picture?” asked Monica Sugaray, who tests newly arrived students for Arlington public schools.

Mikal, 16, looked at the image of a man moving through water. “Swimming,” she said.

Then the questions got more difficult. She read an essay about immigration. “What in this essay is an opinion?” Sugaray asked.

Mikal stared at the words, but nothing came to her.

Such questions are part of a rite of passage for more than 3,000 students from immigrant families who enroll each year in Arlington schools.

About half are foreign-born; half are born in the United States and speak a language other than English at home. They are the sons and daughters of ambassadors, refugees, businessmen and taxi drivers, and together they are fluent in 96 languages.

In one of the region’s highest-achieving school systems, officials have undertaken a monumental effort to integrate these students and their families, translating thousands of documents and report cards, sending dozens of interpreters to parent-teacher conferences.

That quest — intensely personal and sometimes plagued by cultural pitfalls — begins here, in an office decorated with flags, posters and artifacts from around the world. The Language Services and Registration Center is Arlington’s academic Ellis Island, a place where many immigrants will have their first extensive interaction with a government entity in the United States.

Each day there are new challenges: the Mongolians who refused to send their children to school for fear of being deported; the sons and daughters of human trafficking victims from Thailand; the Chinese teenager who arrived unaccompanied, his life savings in his back pocket. Officials at the center are quick to tell parents that they do not — and cannot legally — check the immigration status of students.

Mikal arrived at the center with her father, Efrem Siele, 12-year-old brother Rimon and sister Rodas, 9. Efrem Siele left Eritrea six years ago, after the country’s war with Ethi­o­pia. He got a job at a gas station and saved up to bring the rest of his family to the United States.

That day in May, the father and his children sat across from Ahmed Osman, a bilingual family resource assistant. Eight years ago, Osman had brought his own children to the center after arriving from Sudan. Back then, he asked questions that he now answers daily.

“Are these the best schools in Arlington?” Siele asked, after hearing that his children would attend Abingdon Elementary School, Thomas Jefferson Middle School and Wakefield High School.

“These are very good schools,” Osman said.

“Will they get to stay in their grades?” Siele asked.

“We’ll have to see what the test scores look like,” Osman said, scanning a pile of Eritrean report cards and course work, trying to make sense of the academic patchwork that many immigrants bring to the center.

Mikal wanted desperately not to repeat 10th grade. But her English needed help; she’d learned much of her vocabulary from watching movies such as “Twilight” and “Titanic.” There were also questions about the quality of her education back home. How does a math or history course in Eritrea compare to one in Virginia? Officials often wrestle with such issues.

Even trickier in Mikal’s case: There was only a month left in the school year.

The center’s most basic responsibility is to gauge English language skills and to place students in appropriate courses. About 20 percent of Arlington’s 21,000 students are classified as having limited English proficiency. There is a similar fraction of English language learners in other Northern Virginia cities and counties, but data on foreign-born students are scant.

Testing at the center is extensive. Students are assessed not only in English but also in their native tongue. “Foundation for the second language comes from the first language,” said Silvia Gonzalez Koch, the center’s coordinator.

The federal government requires school systems to assess the language skills of foreign-born students — a mandate that takes many forms across the country. In the Washington area, most systems maintain offices like Arlington’s, tailored to the needs of foreign families.

Prince George’s County has the International Student Counseling Office. Montgomery County has the Residency and International Admissions office. Fairfax County has the Student Registration Center. Prince William has the Central Registration and World Languages Center.

The Arlington center, which opened in 1979, offers a unique window into the county’s demographic shifts. When Salvadorans began arriving in the 1980s, when Mongolians came in the 1990s, when Iraqis started trickling in during the past decade, the center’s employees were among the first to note the influx.

But no matter how refined the registration process, no matter how directed the placement exams, the transition to American public school can be rocky.

In late May, Mikal arrived at Wakefield for her first day of school. The campus was huge compared with her Eritrean school. A counselor described Mikal’s schedule at Wakefield — how she would have to crisscross the hallways in different ways depending on whether it was an “A” day or a “B” day.

Mikal’s eyes widened. She rolled her head back. She was starting to freak out, and she hadn’t even attended her first class.

“I can’t do this,” she told an Eritrean family friend, Ghenet Solomon, in Tigrinya, her native language.

“You’ll be fine. It gets easier,” said Ghenet, 16, who had immigrated nearly a year earlier.

They parted ways, and Mikal walked into her first American classroom. Social studies teacher Khiet Dang pulled down a map in the front of the classroom.

“Can you show us where your country is?” he asked Mikal.

She walked slowly to the map. Without saying a word, she pointed to the Horn of Africa and went back to her seat.

“Good,” Dang said. “Very good.”

It was a long day, and a long week. Mikal kept quiet during lunch hours. Sometimes she got angry and told friends they were being childish.

“It’s not like this back home,” she told them.

But the days got easier, she said in June after the school year ended. And even though it looks as if she’ll have to repeat 10th grade, she is warming up to American education — even to the idea of summer school, which she’ll begin in a few weeks. At the registration center, no one is surprised.

“It can be a difficult transition in the beginning,” Osman said. “But they almost always adapt, and they succeed.”